The subject matter disclosed herein relates generally to additive manufacturing systems and, more particularly, to additive manufacturing systems including imaging devices for imaging melted particulate during an additive manufacturing process.
At least some additive manufacturing systems involve the buildup of a metal component to make a net, or near net shape component. These systems produce complex components from expensive materials at a reduced cost and with improved manufacturing efficiency. Some known additive manufacturing systems, such as Direct Metal Laser Melting (DMLM), Selective Laser Sintering (SLS), Direct Metal Laser Sintering (DMLS), Selective Laser Melting (SLM) and LaserCusing systems, fabricate components using a focused energy source, such as a laser device or an electron beam generator, and a particulate, such as a powdered metal.
In some known additive manufacturing systems, component quality is reduced due to excess heat and/or variation in heat being transferred to the metal powder by the focused energy source within the melt pool. For example, sometimes local overheating occurs, particularly at overhangs. In addition, in some known additive manufacturing systems, component surface quality, particularly at overhangs or downward facing surfaces, is reduced due to the variation in conductive heat transfer between the powdered metal and the surrounding solid material of the component. For example, the melt pool produced by the focused energy source sometimes becomes too large resulting in the melted metal spreading into the surrounding powdered metal as well as the melt pool penetrating deeper into the powder bed, pulling in additional powder into the melt pool. The increased melt pool size and depth, and the flow of molten metal result in a poor surface finish of the overhang or downward facing surface.
In addition, in some known additive manufacturing systems, the component's dimensional accuracy and small feature resolution is reduced due to melt pool variations because of the variability of thermal conductivity of the subsurface structures and metallic powder. As the melt pool size varies, the accuracy of printed structures varies, especially at the edges of features.
At least some known additive manufacturing systems include imaging devices to generate images of portions of the melt pool during the fabrication process. The imaging devices include a camera with a shutter that is opened for extremely short periods of time. The imaging devices track the focused energy source to capture light during the melting process. However, the imaging devices generate images of only portions of the melt pool. Moreover, the imaging devices generate images of portions of the melt pool without reference to specific positions. In addition, the imaging devices require complex programming and apparatus customized for the specific additive manufacturing system.